title: Specific T helper cell requirement for optimal induction of cytotoxic T lymphocytes against major histocompatibility complex class II negative tumors.
abstract: This study shows that induction of tumor-specific CD4+ T cells by vaccination with a specific viral T helper epitope, contained within a synthetic peptide, results in protective immunity against major histocompatibility complex (MHC) class II negative, virus-induced tumor cells. Protection was also induced against sarcoma induction by acutely transforming retrovirus. In contrast, no protective immunity was induced by vaccination with an unrelated T helper epitope. By cytokine pattern analysis, the induced CD4+ T cells were of the T helper cell 1 type. The peptide-specific CD4+ T cells did not directly recognize the tumor cells, indicating involvement of cross-priming by tumor-associated antigen-presenting cells. The main effector cells responsible for tumor eradication were identified as CD8+ cytotoxic T cells that were found to recognize a recently described immunodominant viral gag-encoded cytotoxic T lymphocyte (CTL) epitope, which is unrelated to the viral env-encoded T helper peptide sequence. Simultaneous vaccination with the tumor-specific T helper and CTL epitopes resulted in strong synergistic protection. These results indicate the crucial role of T helper cells for optimal induction of protective immunity against MHC class II negative tumor cells. Protection is dependent on tumor-specific CTLs in this model system and requires cross-priming of tumor antigens by specialized antigen-presenting cells. Thus, tumor-specific T helper epitopes have to be included in the design of epitope-based vaccines.
authors.affiliation: Department of Immunohematology and Bloodbank, Leiden University Medical Center, 2300 RC Leiden, The Netherlands. ossendorp@rullf2.medfac.leidenuniv.nl
authors.forename: F
authors.initials: F
authors.lastname: Ossendorp
authors.forename: E
authors.initials: E
authors.lastname: Mengedé
authors.forename: M
authors.initials: M
authors.lastname: Camps
authors.forename: R
authors.initials: R
authors.lastname: Filius
authors.forename: C J
authors.initials: CJ
authors.lastname: Melief
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000951:Antigens, Neoplasm / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D004306:Dose-Response Relationship, Immunologic; D007111:Immunity, Cellular; D009052:Leukemia Virus, Murine / Q000276:immunology; D007942:Leukemia, Experimental / Q000276:immunology* / Q000517:prevention & control; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010455:Peptides / Q000276:immunology; D013329:Structure-Activity Relationship; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D014611:Vaccination; D014759:Viral Envelope Proteins / Q000276:immunology; D014764:Viral Proteins / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology
chemical_list: D000951:Antigens, Neoplasm; D010455:Peptides; D014759:Viral Envelope Proteins; D014764:Viral Proteins; D014765:Viral Vaccines